Electric motor with ball bearing assembly for rotary shaft

Abstract

An electric motor includes a rotor having a rotary shaft, a pair of ball bearings for supporting the rotary shaft, and two brackets having bearing housings for holding the ball bearings. The motor further includes a washer between one of the ball bearings and an end wall of one of the bearing housings. The washer includes a plurality of claws. The washer is configured including a ring-shaped yoke and the claws the center parts of which are fastened to the yoke. These claws are configured to be bent in a U-shape, and the center part of the U-shape is fastened to the yoke.

The invention claimed is: 
     
       1. An electric motor comprising:
 a rotor including a rotary shaft; 
 first and second ball bearings supporting the rotary shaft, at least the first ball bearing having a ball, a bearing seal plate and a side wall; 
 first and second brackets including first and second bearing housings that hold the first and second ball bearings, respectively, the first bearing housing having an end wall; and 
 a washer being disposed between the side wall of the first ball bearing and the end wall of the first bearing housing, 
 wherein the bearing seal plate is spaced apart from the ball in a direction along the rotary shaft, 
 the washer includes a plurality of claws, each of the claws protruding in the direction along the rotary shaft, and 
 at least one of the claws faces and is wedged against at least one of the bearing seal plate and the end wall of the first bearing housing so as to generate a frictional force in the circumferential direction between the at least one of the claws and the at least one of the bearing seal plate and the end wall of the first bearing housing. 
 
     
     
       2. The electric motor according to  claim 1 ,
 wherein the washer includes a ring-shaped yoke, 
 each of the plurality of the claws includes a center part, the center part being fastened to the yoke, and 
 each of the claws is bent in a U-shape, and is wedged against at least one of the bearing seal plate and the end wall of the first bearing housing by both ends of the U-shape protruding in a direction along the rotary shaft. 
 
     
     
       3. The electric motor according to  claim 2 , wherein the yoke has a corrugated shape. 
     
     
       4. The electric motor according to  claim 2 , wherein both distal portions of the both ends of the U-shape are protruding in the direction along the rotary shaft. 
     
     
       5. The electric motor according to  claim 1 , wherein the second ball bearing and the second bearing housing are fixed to each other. 
     
     
       6. The electric motor according to  claim 1 , wherein the claws are disposed to face a side providing lower one of μ1 and μ2 where μ1 is a static friction coefficient between the first ball bearing and the claws of the washer, and μ2 is a static friction coefficient between the end wall of the first bearing housing and the claws of the washer. 
     
     
       7. The electric motor according to  claim 1 , wherein the claws are disposed facing both sides such that the claws face both the first ball bearing and the end wall of the first bearing housing. 
     
     
       8. The electric motor according to  claim 1 , wherein at least one of the first and second brackets is made of a synthetic resin. 
     
     
       9. The electric motor according to  claim 1 , wherein the bearing seal plate is of a rubber type, the bearing seal plate being held in contact with the claws. 
     
     
       10. The electric motor according to  claim 1 , wherein an end-wall step height is disposed in the end wall of the first bearing housing facing the claws, the end-wall step height fitting into the claws. 
     
     
       11. The electric motor according to  claim 1 , wherein a portion of the at least one of the bearing seal plate and the end wall of the first bearing housing in contact with the at least one of the claws is at a position overlapping the ball as viewed in the direction along the rotary shaft.